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Article published with DEMEAU interim results on trigger values using CALUX bioassays

In May 2013, interim results were published in Environment International by scientists from BioDetection Systems B.V., the National Institute for Public Health and the Environment (RIVM) and the DEMEAU partner KWR Watercycle Research Institute.

To screen for hormonal activity in water samples, highly sensitive in vitro CALUX bioassays are available which allow detection of estrogenic (ERα), androgenic (AR), progestagenic (PR), and glucocorticoid (GR) activities. This paper presents trigger values for the ERα, AR, PR, and GR CALUX bioassays for agonistic hormonal activities in (drinking) water, which define a level above which human health risk cannot be waived a priori and additional examination of specific endocrine activity may be warranted. The trigger values are based on 1) acceptable or tolerable daily intake (ADI/TDI) values of specific compounds, 2) pharmacokinetic factors defining their bioavailability, 3) estimations of the bioavailability of unknown compounds with equivalent hormonal activity, 4) relative endocrine potencies, and 5) physiological, and drinking water allocation factors. As a result, trigger values of 3.8 ng 17β-estradiol (E2)-equivalents (eq)/L, 11 ng dihydrotestosterone (DHT)-eq/L, 21 ng dexamethasone (DEX)-eq/L, and 333 ng Org2058-eq/L were derived. Benchmark Quotient (BQ) values were derived by dividing hormonal activity in water samples by the derived trigger using the highest concentrations detected in a recent, limited screening of Dutch water samples, and were in the order of (value) AR (0.41) > ERα (0.13) > GR (0.06) > PR (0.04). The application of trigger values derived in the present study can help to judge measured agonistic hormonal activities in water samples using the CALUX bioassays and help to decide whether further examination of specific endocrine activity followed by a subsequent safety evaluation may be warranted, or whether concentrations of such activity are of low priority with respect to health concerns in the human population. For instance, at one specific drinking water production site ERα and AR (but no GR and PR) activities were detected in drinking water, however, these levels are at least a factor 83 smaller than the respective trigger values, and therefore no human health risks are to be expected from hormonal activity in Dutch drinking water from this site.